Meysam Kamali, Husnain Tansar, Ebrahim Ahmadisharaf, Nasrin Alamdari
Study region Hillsborough Watershed (374 km 2 ) in Midwest Florida. Study focus Green infrastructures (GIs) are implemented in urban areas to restore natural hydrology. Past studies have evaluated the performance of GIs for runoff reduction, but detailed fine-scale models have been rarely applied. Here, we evaluated the performance of GIs at two scales—fine-scale (3800 subwatersheds) and full watershed—under various rainfall intensities (2- to 200-yr) using Storm Water Management Model (SWMM). Six GI scenarios—individual (bioretention [BR], grassed swale [GS], green roof [GR], rain barrel [RB], cistern [CS] and infiltration trench [IT]), suitability-based (maximum one GI in each subwatershed) and combined—were evaluated considering ∼18,000 hydraulic structures ("detailed" component of our modeing). New hydrological insights for the region With 26.8–29.1 % reduction of runoff volume and 78.6–82.4 % of peak, IT showed the best performance at the fine-scale under the 5-yr rainfall event. A combination of BR, GS, IT and CS outperformed the individual GI scenarios in reducing runoff volume (up to 78.6 %). Subwatersheds with larger imperviousness benefited most from BR, RB, CS and IT in terms of runoff volume reductions because of the higher retrofit rate. The efficiency of GR for delaying time-to-peak was less in more intense rainfall events. Our comparisons showed that fine-scale modeling revealed subwatersheds with disproportionately high or low GI effectiveness, which were masked in the coarse-scale full watershed model.